Various engineered systems use pressure sensors with linear outputs to track changes in operation before such operational conditions become critical. These pressure sensors may also include pressure switches that trigger quick reaction in response to a measured critical condition. Silicon-based pressure sensors and/or switches, such as sensors using microelectromechanical system (MEMS) technology, have recently been used for detection of pressure, especially in systems that also include electrical circuits. Such MEMS pressure sensors usually include piezo-resistive or capacitative components to measure ambient pressure in non-critical conditions.
MEMS switches include components like deflecting beams or cantilevers that make galvanic contact with each other. Similarly, some MEMS switches include beam-suspended, perforated plates that change an attached electrical circuit's impedance capacitatively. However, both types of these existing MEMS switches require perfect sealing from the environment to avoid degradation, such as contact degradation. Such requirements impose severe restraints on the packaging of such switches.
In addition, certain applications require immediate action when a critical pressure threshold is reached. However, many mechanical safety measures (e.g., mechanical vanes, etc.) used to respond to such measured pressures may not allow electrical or electronic control. Similarly, electronic sensors may require constant power to operate correctly and may still exhibit a more delayed response when compared to like mechanical sensors.